Bio-based environment-friendly breathable foaming material and preparation method thereof

Abstract

The invention discloses a bio-based environment-friendly breathable foam material and a preparation method thereof. The bio-based environment-friendly breathable foam material is prepared from the following raw materials: modified starch, a plasticizer, a foaming agent, a nucleating agent, nano filler and water, the specific formula comprises the following raw materials: 70-90 parts of starch, 1-5 parts of a plasticizer, 0.5-2 parts of a foaming agent, 0.5-1 part of a nucleating agent, 1-2 parts of a nano filler and 10-15 parts of water. The starch and the polylactic acid are modified and blended, hydrogen bonds can be formed between hydroxyl groups in polylactic acid molecules and hydroxyl groups in starch molecules, the compatibility between the polylactic acid molecules and the starch molecules is enhanced, foaming is more uniform and stable, a certain amount of nano-filler is added, and due to the fact that the nano-filler has the characteristics of high strength and high modulus, the foaming performance is improved. When the starch-based foaming material is added, a network structure can be formed, the internal support of the material is enhanced, and the tensile strength and the bending strength are improved, so that the advantages of all the components are integrated, and the mechanical property of the foaming material is remarkably enhanced.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of bio-based foaming materials, in particular to a bio-based environmentally friendly breathable foaming material and a preparation method thereof. BACKGROUND

[0002] With the acceleration of global industrialization, environmental problems are becoming increasingly serious, and people have higher requirements for the environmental performance and sustainability of materials. Traditional foaming materials are mainly based on petroleum-based raw materials, which not only consume a large amount of non-renewable resources during production and use, but also cause serious pollution to the environment. For example, discarded traditional foam plastics are difficult to degrade in the natural environment, and long-term accumulation leads to soil pollution and ecological destruction. The greenhouse gases emitted during their production also exacerbate global warming. In this context, bio-based environmentally friendly breathable foaming materials have emerged. This kind of material uses renewable biomass resources as raw materials, such as plant fibers, starch, vegetable oil, etc., and has the advantages of being renewable, biodegradable, low energy consumption, and low pollution. The use of bio-based environmentally friendly breathable foaming materials can effectively reduce the dependence on non-renewable resources such as petroleum, reduce carbon emissions, and reduce environmental pollution, in line with the concept of sustainable development, However, the bio-based environmentally friendly breathable foaming material currently in practical application has insufficient heat resistance and may soften, decompose, etc. under high temperature conditions, and has low strength, which is prone to deformation, rupture, etc. under certain pressure or tension, and cannot meet the requirements of some application scenarios with high material strength requirements, which seriously restricts the further promotion and application of bio-based environmentally friendly breathable foaming materials. SUMMARY

[0003] In view of the defects of the prior art, the purpose of the present application is to provide a bio-based environmentally friendly breathable foaming material and a preparation method thereof to solve the problems raised in the background art.

[0004] The technical problem solved by the present application adopts the following technical solution: The present application provides a bio-based environmentally friendly breathable foaming material, which comprises the following raw materials: modified starch, plasticizer, foaming agent, nucleating agent, nano filler, water; The specific formula comprises the following raw materials: starch 70-90 parts, plasticizer 1-5 parts, foaming agent 0.5-2 parts, nucleating agent 0.5-1 part, nano filler 1-2 parts, and water 10-15 parts.

[0005] Preferably, the bio-based environmentally friendly breathable foaming material comprises the following raw materials: starch 80 parts, plasticizer 3 parts, foaming agent 1 part, nucleating agent 0.8 part, nano filler 1.5 parts, and water 12 parts.

[0006] Preferably, the preparation method of the modified starch is as follows: S1. Mix starch and polylactic acid evenly in a ratio of 100:(10-30), and then use a machine... The mixture is then mixed using a high-speed mechanical mixer. S2. Add the mixed materials to a solution containing epichlorohydrin, and add 2-3% sodium hydroxide by weight. Stir and react at 40-60℃ for 7-8 hours to allow the cross-linking reaction to proceed fully. S3. After the reaction is complete, cross-linked modified starch is obtained through filtration, washing and drying.

[0007] Preferably, the plasticizer is a compound system of glycerol and sorbitol, and the mass ratio of glycerol to sorbitol is 10:(5-7).

[0008] Preferably, the foaming agent is a composite foaming system of sodium bicarbonate and citric acid, wherein the mass ratio of sodium bicarbonate to citric acid is 10:(2-3).

[0009] Preferably, the nucleating agent is selected from one or more of silica, talc, titanium dioxide, and montmorillonite with a fineness of 7000-8500 mesh.

[0010] Preferably, the nanofiller is nanocellulose or nanoclay.

[0011] This invention also provides a method for preparing a bio-based environmentally friendly breathable foam material, comprising the following steps: Step 1: Remove impurities and foreign matter from the modified starch through screening and impurity removal processes, and reduce the moisture content of the modified starch to below 5% using vacuum drying technology. Step 2: In a high-speed mixer, thoroughly mix the dried modified starch with plasticizer, foaming agent, nucleating agent, nanofiller, and water; Step 3: Set the temperature of the barrel and the die head. The temperature from the hopper end to the die head end is set to 6 temperature segments: 100℃, 125℃, 145℃, 165℃, 175℃, and 165℃. Step 4: The mixed materials from Step 2 are fed into a twin-screw extruder and extruded through a high-compression twin-screw extruder. After foaming and molding, the material is cooled and shaped to obtain a bio-based environmentally friendly breathable foam material.

[0012] Preferably, the compression ratio of the twin-screw extruder is 5-6, and the length-to-diameter ratio of the twin-screw extruder is (35-40):1.

[0013] Preferably, the twin-screw extruder uses a flat die, and the rotational speed of the twin-screw extruder is controlled at 320-400 r / min.

[0014] The present invention discloses a bio-based environmentally friendly breathable foam material and its preparation method. By modifying and blending starch with polylactic acid (PLA), hydrogen bonds can be formed between the hydroxyl groups in PLA molecules and starch molecules, enhancing the compatibility between the two and making the foaming more uniform and stable. This synergistic effect not only utilizes the good mechanical properties and thermal stability of PLA to improve the strength and heat resistance of starch-based foam materials, but also ensures the overall environmental performance of the material due to the biodegradability of PLA, thus improving the performance of the foam material. Furthermore, a certain amount of nanofiller is added. Due to the high strength and high modulus of nanofiller, when added to starch-based foam materials, it can form a network structure, enhance the internal support of the material, and improve tensile and flexural strength. Thus, the advantages of each component are combined to significantly enhance the mechanical properties of the foam material.

[0015] Compared with the prior art, the present invention has the following beneficial effects: In terms of mechanical properties, the present invention has a tensile strength of 3MPa and a flexural strength of 4MPa, which can meet the requirements of general packaging and cushioning materials. It effectively absorbs and disperses impact forces, provides reliable protection for fragile items, and the material has a density of only 0.2-0.3g / cm³, making it lightweight and easy to degrade. Detailed Implementation

[0016] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to specific examples. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0017] This embodiment of the present invention provides a bio-based environmentally friendly breathable foam material, comprising the following raw materials: modified starch, plasticizer, foaming agent, nucleating agent, nanofiller, and water; Its specific formula includes the following raw materials: 70-90 parts starch, 1-5 parts plasticizer, 0.5-2 parts foaming agent, 0.5-1 part nucleating agent, 1-2 parts nanofiller, and 10-15 parts water.

[0018] The bio-based environmentally friendly breathable foam material of this embodiment includes the following raw materials: 80 parts starch, 3 parts plasticizer, 1 part foaming agent, 0.8 parts nucleating agent, 1.5 parts nanofiller, and 12 parts water.

[0019] The method for preparing the modified starch in this embodiment is as follows: S1. Mix starch and polylactic acid evenly in a ratio of 100:(10-30), and then use a machine... The mixture is then mixed using a high-speed mechanical mixer. S2, the mixed material is added to a solution containing epichlorohydrin, and 2-3% by weight of sodium hydroxide is added, and the reaction is stirred at a temperature of 40-60°C for 7-8 hours to fully carry out the crosslinking reaction; S3, after the reaction is completed, the crosslinked modified starch is obtained through the steps of filtration, washing and drying.

[0020] The plasticizer of the embodiment is a compound system of glycerol and sorbitol, and the mass ratio of glycerol to sorbitol is 10: (5-7), which can effectively reduce the glass transition temperature of starch and improve its plasticity.

[0021] The foaming agent of the embodiment is a composite foaming system of sodium bicarbonate and citric acid, and the mass ratio of sodium bicarbonate to citric acid is 10: (2-3); thus, decomposition reaction occurs when heated, generating gas. These generated gases form bubble nuclei in the modified starch matrix. With the continuous generation and diffusion of gas, the bubble nuclei gradually grow to form a pore structure, achieving the foaming effect.

[0022] The nucleating agent of the embodiment is selected from one or more of silica with fineness of 7000-8500 mesh, talc, titanium dioxide, and montmorillonite.

[0023] The nanofiller of the embodiment is nanocellulose or nanoclay.

[0024] The preparation method of the biobased environmentally friendly breathable foaming material of the embodiment includes the following steps: Step one, impurities and foreign matters in the modified starch are removed through screening and impurity removal processes, and the moisture content of the modified starch is reduced to below 5% by using vacuum drying technology to ensure the stability of the subsequent processing process; Step two, the dried modified starch is fully mixed with the plasticizer, foaming agent, nucleating agent, nanofiller, and water in a high-speed mixer; Step three, the temperature of the barrel and die head is set, and the temperature from the hopper end to the die head end is set to six stages: 100°C, 125°C, 145°C, 165°C, 175°C, and 165°C. The low temperature at the front end can make the material soften and transport initially, and the high temperature at the rear end can make the material fully melt and plasticize, preparing for foaming. Step four, the mixed material in step two is put into a double screw extruder, extruded by a high compression ratio double screw extruder, and then cooled and shaped after foaming to obtain a biobased environmentally friendly breathable foaming material. Cooling and shaping can maintain a stable shape, and the cooling method can be air cooling or water cooling.

[0025] The compression ratio of the double screw extruder of the embodiment is 5-6, and the length-diameter ratio of the double screw extruder is (35-40): 1, which has good material conveying and mixing capacity.

[0026] The twin-screw extruder in this embodiment uses a flat die, and the speed of the twin-screw extruder is controlled at 320-400 r / min. Example 1

[0027] This embodiment of the present invention provides a bio-based environmentally friendly breathable foam material, comprising the following raw materials: modified starch, plasticizer, foaming agent, nucleating agent, nanofiller, and water; Its specific formula includes the following raw materials: 70 parts starch, 1 part plasticizer, 0.5 parts foaming agent, 0.5 parts nucleating agent, 1 part nanofiller, and 10 parts water.

[0028] The method for preparing the modified starch in this embodiment is as follows: S1. Mix starch and polylactic acid in a ratio of 100:10 until homogeneous, then use a machine... The mixture is then mixed using a high-speed mechanical mixer. S2. Add the mixed materials to a solution containing epichlorohydrin, and add 2% sodium hydroxide by weight. Stir the mixture at 40°C for 7 hours to allow the cross-linking reaction to proceed fully. S3. After the reaction is complete, cross-linked modified starch is obtained through filtration, washing and drying.

[0029] In this embodiment, the plasticizer is a compound system of glycerol and sorbitol, with a mass ratio of glycerol to sorbitol of 10:5.

[0030] In this embodiment, the foaming agent is a composite foaming system of sodium bicarbonate and citric acid, with a mass ratio of sodium bicarbonate to citric acid of 10:2.

[0031] In this embodiment, the nucleating agent is selected from one or more of the following: silica with a fineness of 7000 mesh, talc, titanium dioxide, and montmorillonite.

[0032] The nanofiller in this embodiment is nanocellulose or nanoclay.

[0033] This embodiment describes a method for preparing a bio-based, environmentally friendly, breathable foam material, including the following steps: Step 1: Remove impurities and foreign matter from the modified starch through screening and impurity removal processes, and reduce the moisture content of the modified starch to below 5% using vacuum drying technology. Step 2: In a high-speed mixer, thoroughly mix the dried modified starch with plasticizer, foaming agent, nucleating agent, nanofiller, and water; Step 3: Set the temperature of the barrel and the die head. The temperature from the hopper end to the die head end is set to 6 temperature segments: 100℃, 125℃, 145℃, 165℃, 175℃, and 165℃. Step 4: The mixed materials from Step 2 are fed into a twin-screw extruder and extruded through a high-compression twin-screw extruder. After foaming and molding, the material is cooled and shaped to obtain a bio-based environmentally friendly breathable foam material.

[0034] The twin-screw extruder in this embodiment has a compression ratio of 5 and a length-to-diameter ratio of 35:1.

[0035] The twin-screw extruder in this embodiment uses a flat die, and the speed of the twin-screw extruder is controlled at 320 r / min. Example 2

[0036] This embodiment of the present invention provides a bio-based environmentally friendly breathable foam material, comprising the following raw materials: modified starch, plasticizer, foaming agent, nucleating agent, nanofiller, and water; Its specific formula includes the following raw materials: 80 parts starch, 3 parts plasticizer, 1 part foaming agent, 0.8 parts nucleating agent, 1.5 parts nanofiller, and 12 parts water.

[0037] The method for preparing the modified starch in this embodiment is as follows: S1. Mix starch and polylactic acid evenly in a ratio of 100:20, and then use a machine... The mixture is then mixed using a high-speed mechanical mixer. S2. Add the mixed materials to a solution containing epichlorohydrin and add 2.5% sodium hydroxide by weight. Stir the mixture at 50°C for 7.5 hours to allow the cross-linking reaction to proceed fully. S3. After the reaction is complete, cross-linked modified starch is obtained through filtration, washing and drying.

[0038] In this embodiment, the plasticizer is a compound system of glycerol and sorbitol, with a mass ratio of glycerol to sorbitol of 10:6.

[0039] In this embodiment, the foaming agent is a composite foaming system of sodium bicarbonate and citric acid, with a mass ratio of sodium bicarbonate to citric acid of 10:2.5.

[0040] In this embodiment, the nucleating agent is selected from one or more of the following: silica with a fineness of 7500 mesh, talc, titanium dioxide, and montmorillonite.

[0041] The nanofiller in this embodiment is nanocellulose or nanoclay.

[0042] This embodiment describes a method for preparing a bio-based environmentally friendly breathable foam material, comprising the following steps: Step 1: Remove impurities and foreign matter from the modified starch through screening and impurity removal processes, and reduce the moisture content of the modified starch to below 5% using vacuum drying technology. Step 2: In a high-speed mixer, thoroughly mix the dried modified starch with plasticizer, foaming agent, nucleating agent, nanofiller, and water; Step 3: Set the temperature of the barrel and the die head. The temperature from the hopper end to the die head end is set to 6 temperature segments: 100℃, 125℃, 145℃, 165℃, 175℃, and 165℃. Step 4: The mixed materials from Step 2 are fed into a twin-screw extruder and extruded through a high-compression twin-screw extruder. After foaming and molding, the material is cooled and shaped to obtain a bio-based environmentally friendly breathable foam material.

[0043] The twin-screw extruder in this embodiment has a compression ratio of 5 and a length-to-diameter ratio of 38:1.

[0044] The twin-screw extruder in this embodiment uses a flat die, and the speed of the twin-screw extruder is controlled at 380 r / min. Example 3

[0045] This embodiment of the present invention provides a bio-based environmentally friendly breathable foam material, comprising the following raw materials: modified starch, plasticizer, foaming agent, nucleating agent, nanofiller, and water; Its specific formula includes the following raw materials: 90 parts starch, 5 parts plasticizer, 0.2 parts foaming agent, 1 part nucleating agent, 2 parts nanofiller, and 15 parts water.

[0046] The method for preparing the modified starch in this embodiment is as follows: S1. Mix starch and polylactic acid evenly in a ratio of 100:30, and then use a machine... The mixture is then mixed using a high-speed mechanical mixer. S2. Add the mixed materials to a solution containing epichlorohydrin and add 3% sodium hydroxide by weight. Stir the mixture at 60°C for 8 hours to allow the cross-linking reaction to proceed fully. S3. After the reaction is complete, cross-linked modified starch is obtained through filtration, washing and drying.

[0047] In this embodiment, the plasticizer is a compound system of glycerol and sorbitol, with a mass ratio of glycerol to sorbitol of 10:7.

[0048] In this embodiment, the foaming agent is a composite foaming system of sodium bicarbonate and citric acid, with a mass ratio of sodium bicarbonate to citric acid of 10:3.

[0049] In this embodiment, the nucleating agent is selected from one or more of the following: silica with a fineness of 8500 mesh, talc, titanium dioxide, and montmorillonite.

[0050] The nanofiller in this embodiment is nanocellulose or nanoclay.

[0051] The preparation method of the biobased environmentally friendly breathable foamed material of the embodiment comprises the following steps: Step one: remove impurities and foreign matters in the modified starch through screening and impurity removal process, and reduce the water content of the modified starch to below 5% by using vacuum drying technology; Step two: mix the dried modified starch, plasticizer, foaming agent, nucleating agent, nano filler and water in a high-speed mixer; Step three: set the temperature of the barrel and die head, and the temperature from the hopper end to the die head end is set to six segments in turn: 100℃, 125℃, 145℃, 165℃, 175℃, 165℃; Step four: put the mixed material in step two into a double screw extruder, extrude it through a high compression ratio double screw extruder, cool and shape it after foaming and molding, and obtain the biobased environmentally friendly breathable foamed material.

[0052] The compression ratio of the double screw extruder of the embodiment is 5-6, and the length-diameter ratio of the double screw extruder is 40:1.

[0053] The double screw extruder of the embodiment adopts a flat die, and the rotating speed of the double screw extruder is controlled at 400r / min. Comparative Example 1

[0054] Unlike Examples 1-3, the biobased environmentally friendly breathable foamed material is prepared using ordinary raw materials.

[0055] The products of Examples 1-3 and Comparative Example 1 are tested for performance; Twenty biobased environmentally friendly breathable foamed material samples are made, five in each group, a total of four groups, each group corresponding to Examples 1-3 and Comparative Example 1 and numbered A / B / C / D, and finally the biobased environmentally friendly breathable foamed material samples of groups A / B / C / D are detected, and the detection results are as follows.

[0056]

[0057] As can be seen from Examples 1-3, the biobased environmentally friendly breathable foamed material and its preparation method made using the present application have a tensile strength of 3MPa and a bending strength of 4MPa in terms of mechanical properties, which can meet the use requirements of general packaging and cushioning materials, effectively absorb and disperse impact force, and provide reliable protection for fragile items, and the density of the material is only 0.2-0.3g / cm³, which is light in weight and easy to degrade.

[0058] As can be seen from Example 3 and Comparative Example 1, the modification and blending of starch and polylactic acid, and the addition of a certain amount of nano filler, can enhance the internal support of the material and improve the tensile strength and bending strength.

[0059] The innovation of the present application is that: The present application can form hydrogen bonds between hydroxyl groups in the polylactic acid molecules and the starch molecules by modifying and blending starch and polylactic acid, thereby enhancing the compatibility between the two, making the foaming more uniform and stable, and the synergistic effect not only utilizes the good mechanical properties and thermal stability of polylactic acid to improve the strength and heat resistance of the starch-based foaming material, but also ensures the overall environmental performance of the material by the biodegradability of polylactic acid, improves the performance of the foaming material, and adds a certain amount of nano filler, which has the characteristics of high strength and high modulus, and can form a network structure when added to the starch-based foaming material, thereby enhancing the internal support of the material, improving the tensile strength and bending strength, and thereby comprehensively utilizing the advantages of each component to significantly enhance the mechanical properties of the foaming material.

[0060] It is apparent for those skilled in the art that the present application is not limited to the details of the above exemplary embodiments, but can be implemented in other concrete forms without departing from the spirit or essential characteristics of the present application. Therefore, the embodiments should be considered in all aspects as illustrative and not restrictive, and the scope of the present application is defined by the appended claims rather than the above description, and all changes falling within the meaning and range of the equivalent elements of the claims are intended to be embraced in the present application.

[0061] Furthermore, it should be understood that although the present specification is described in terms of embodiments, not every embodiment contains only one independent technical solution, and the description of the specification is only for the sake of clarity, and those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that those skilled in the art can understand.

Claims

1. A bio-based, environmentally friendly, breathable, foamed material, characterized in that, Comprise the following raw materials: modified starch, plasticizer, foaming agent, nucleating agent, nano filler, water; Its specific formula includes the following raw materials (by mass fraction): starch 70-90 parts, plasticizer 1-5 parts, foaming agent 0.5-2 parts, nucleating agent 0.5-1 part, nano filler 1-2 parts, water 10-15 parts.

2. The bio-based, environmentally friendly, breathable, foamed material according to claim 1, characterized in that, Comprise the following raw materials: Starch 80 parts, plasticizer 3 parts, foaming agent 1 part, nucleating agent 0.8 part, nano filler 1.5 parts, water 12 parts.

3. The bio-based, environmentally friendly, breathable, foamed material according to claim 1, characterized in that, The preparation method of the modified starch is as follows: S1, mix the starch and polylactic acid uniformly according to the ratio of 100: (10-30), and then mix them by using a mechanical high-speed mixer; S2, add the mixed material into a solution containing epichlorohydrin, and add 2-3% by weight of sodium hydroxide, stir and react at 40-60℃ for 7-8 hours to make the crosslinking reaction fully proceed; S3, after the reaction is completed, the crosslinked modified starch is obtained through the steps of filtration, washing and drying. The plasticizer is a compound system of glycerol and sorbitol, and the mass ratio of glycerol to sorbitol is 10: (5-7).

4. The bio-based, environmentally friendly, breathable, foamed material according to claim 1, characterized in that, The foaming agent is a composite foaming system of sodium bicarbonate and citric acid, and the mass ratio of sodium bicarbonate to citric acid is 10: (2-3).

5. The bio-based, environmentally friendly, breathable, foamed material according to claim 4, characterized in that, The nucleating agent is selected from one or more of silica with fineness of 7000-8500 mesh, talc, titanium dioxide and montmorillonite.

6. The bio-based, environmentally friendly, breathable, foamed material according to claim 5, characterized in that, The nano filler is nano cellulose or nano clay.

7. The bio-based, environmentally friendly, breathable, foamed material according to claim 6, characterized in that, Comprise the following steps:

8. A method of producing a bio-based, environmentally friendly, breathable, foamed material according to any one of claims 1-7, characterized in that, Step one, remove impurities and foreign matters in the modified starch through screening and impurity removal process, and reduce the water content of the modified starch to below 5% by using vacuum drying technology; Step two, mix the dried modified starch with plasticizer, foaming agent, nucleating agent, nano filler and water in a high-speed mixer; Step three, set the temperature of the barrel and die head, and the temperature from the hopper end to the die head end is set to six sections in turn: 100℃, 125℃, 145℃, 165℃, 175℃, 165℃; Step four, put the mixed material in step two into a double screw extruder, extrude it through a high compression ratio double screw extruder, and then cool and shape it after foaming to obtain a biobased environmentally friendly breathable foaming material. The compression ratio of the double screw extruder is 5-6, and the length-diameter ratio of the double screw extruder is (35-40):

1.

9. The method for preparing a bio-based environmentally friendly breathable foam material according to claim 8, characterized in that, The double screw extruder adopts a flat die, and the rotation speed of the double screw extruder is controlled at 320-400 r / min.

10. The method for preparing a bio-based environmentally friendly breathable foam material according to claim 8, characterized in that, ​

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